Post navigation

Fiber Optic Cable Overview

Fiber optic cable is categorized into Single Mode fiber and Multimode fiber. Both use glass fiber to transmit data. Single Mode may offer the best future proof capabilities, because it has advantages in terms of bandwidth and reach for longer distances.

Overview: Single Mode means the Fiber enables one type of light mode to be propagated at a time. While Multimode means the Fiber can propagate multiple modes. The difference between Single Mode and Multimode fiber mainly lies in Fiber Core Diameter, Wavelength, Light Source and Bandwidth.

Optical Fiber Core Diameters: Single Mode Fiber core diameter is much smaller than Multimode fiber. The typical Single Mode Fiber core diameter is 9micron. The typical Multimode Fiber core diameter is 50micron or 62.5micron. The cladding diameter of Single Mode and Multimode fiber is 125micron.

62.5micron Multimode fiber is also called OM1

50micron Multimode fiber can be OM2, OM3, OM4, or OM5

Single Mode fiber is also called OS1 or OS2

Single Mode fiber is suitable for long distance applications, while Multimode fiber is designed for short distance runs.

Single Mode -VS- Multimode Fiber Distance:

Single Mode fiber (OS2); 1Gb Ethernet = 5,000 meters

Multimode fiber (OM1); 1Gb Ethernet = 275 meters

Multimode fiber (OM2, OM3, OM4, or OM5); 1Gb Ethernet = 550 meters

————————————————————————————————

Single Mode fiber (OS2); 10Gb Ethernet = 10 km

Multimode fiber (OM3); 10Gb Ethernet = 300 meters

Multimode fiber OM4); 10Gb Ethernet = 400 meters

Multimode fiber OM5); 10Gb Ethernet = 300 meters

Single Mode fiber is generally geared towards longer distance applications and requires transceivers with lasers that operate at longer wavelengths with smaller spot-size and generally narrower spectral width. These transceiver characteristics combined with the need for higher-precision alignment and tighter connector tolerances to smaller core diameters result in significantly higher transceiver costs and overall higher interconnect costs for Single Mode fiber interconnects. (single mode fiber installations are typically 5 X the cost of a multimode solution)

Single Mode fiber loss is about 0.5 dB per km for 1310 nm sources, 0.4 dB per km for 1550 nm. (1.0 dB/km for premises/0.5 dB/km at either wavelength for outside plant max per EIA/TIA 568) This is roughly a loss of 0.1 dB per 600 (200m) feet for 1310 nm, 0.1 dB per 750 feet (250m) for 1550 nm.

NOTE: Multimode fiber and Single Mode fiber have different core size, and the numbers of light modes that they transmit is also different. If you mix the two fibers, or connect them together directly, you’ll have a large amount of optical loss, resulting in a link flapping or being down.

Color Sheath: According to the TIA-598C standard for non-military applications, single mode cable is coated with yellow outer sheath, and multimode fiber is coated with orange or aqua jacket

Advantages of Single Mode Fiber:

♦ Longer Transmission Distance

♦ Greater Bandwidth Capacity

♦ Increased Transmission Speed

♦ Limited Data Dispersion & External Interference

♦ Less Signal Attenuation

Single Mode fiber doesn’t have modal dispersion, modal noise, and other effects that come with Multimode transmission. Single Mode fiber can carry signals at much higher speeds than Multimode fibers.